Laminated transparent bodies having mar resistant protective coatings

ABSTRACT

Transparent bodies, particularly ophthalmic lenses, having cores of super strong plastic, outer surface layers of abrasion resistant thermosetting resins such as the allyl and methacrylic esters and an intermediate later of a polyamide. The cores are of bisphenol-A polycarbonate, or of a clear, hetereogeneous blend known as ABS, which is a polyblend of three resins. The surface layer is polymerized in situ. The polyamide is selected from among those soluble in alcohol or a mixture of alcohol and hydrocarbons. It serves both as an adhesive to bond the surface layers securely to the cores and as a barrier agent to protect the cores from chemical attack by the monomer of the surface layer material. The surface layer is preferably cured in a mold which defines the shape and surface finish of the completed body.

United States Patent Sheld 15 3,673,055 1 June 27, 1972 Clarence A.Sheld, Rochester, NY. 14617 Busch 8: Lomb, Incorporated, Rochester, NY.

March 30, I970 Inventor: Assignee:

Filed:

Appl. No.:

U.S.Cl ..16l/l83,16l/227, 161/252, 161/256, 161/410 Int. Cl. ..D32b27/30, B32b 27/ 34 Field ofSearch ..161/l83,227,252,256, 1, 161/408-410,165

References Cited UNITED STATES PATENTS 3,520,768 7/1970 Peilstocker etal..161/183 3,539,442 11/1970 Buckley etal. ..l6l/l83 PrimaryExaminer-Harold Ansher Att0rney-Hoffman Stone and Frank C. Parker [57]ABSTRACT Transparent bodies, particularly ophthalmic lenses, havingcores of super strong plastic, outer surface layers of abrasionresistant thermosettin; resins such as the ally] and methacrylic estersand an intermediate later of a polyamide. The cores are of bisphenol-Apolycarbonate, or of a clear, hetereogeneous blend known as ABS, whichis a polyblend of three resins. The surface layer is polymerized insitu. The polyamide is selected from among those soluble in alcohol or amixture of alcohol and hydrocarbons. It serves both as an adhesive tobond the surface layers securely to the cores and as a barrier agent toprotect the cores from chemical attack by the monomer of the surfacelayer material. The surface layer is preferably cured in a mold whichdefines the shape and surface finish of the completed body.

10 Claims, 1 Drawing Figure P'ATENTEDaum ISYZ 3, 573 055 INVENTOR.

CLARENCE A. SHELD BY ATTORNEY LAMINATED TRANSPARENT BODIES HAVING MARRESISTANT PROTECTIVE COATINGS BRIEF DESCRIPTION This invention relatesto transparent bodies and methods of making them having cores of superhigh impact resistant resins, and surface layers of thermosetting resinsthat are much more resistant to abrasion than the resins of the cores.

The extremely high strength and impact resistance of bisphenol-Apolycarbonate are well known. Ophthalmic lenses about three millimetersthick made of it can withstand the impact of a quarter-inch steel ballat speeds of 900 feet per second. Another material of approximatelyequal strength is the plastic called ABS, commercially designatedToyolac plastic and made by Toyo Rayon Company (Japan). It is ahetereogeneous blend of three different polymers: (1) a polymer ofstyrene-acrylonitrile-methylmethacrylate grafted onto a preformed rubberof styrene-butadiene; (2) a terpolymer ofstyrene-acrylonitrile-methylmethacrylate; and (3) a styrene-butadienepolymer. The first polymer is called the gel fraction, and it has arefractive index of 1.529. The second and third polymers together, arecalled the sol fraction, and their refractive indices are both 1.527.The gel fraction constitutes about 30 percent by weight of the ABS, andthe sol fraction about 70 percent. For further details see a paper inthe Journal of Applied Polymer Science, 11, No. 12, 2499 i967 Thesesuper strong materials have not, however, been widely adopted for use inophthalmic safety lenses, because theyare subject to abrasion andscratching, and lenses made of them have not been durable enough tosatisfy industrial buyers.

Accordingly, a principal object of the invention is to improve theabrasion and scratch resistance of bodies made of bisphenol-Apolycarbonate or of ABS polymer blend.

Briefly, according to the invention, it has now been found that surfacelayers of abrasion-resistant materials such as the allyl and methacrylicesters may be applied by polymerization in situ to a body of bisphenol-Apolycarbonate or of ABS, if the body is first coated with a polyamidethat is impenetrable to the monomer of the surface layer. The polyamideserves both as a barrier to prevent chemical attack by the monomer andas a cement to bond the surface layer to the body.

Many different polyamide resins have been found to be effective. Theprincipal limitations governing the choice of a particular one of them,aside from the matter of cost, are that it be soluble in alcohol or inan alcohol-hydrocarbon mixture that does not attack the core material,that it be impenetrable by the monomer of the surface material, and thatthe solution of the polyamide resin in alcohol or thealcohol-hydrocarbon mixture be reasonably flowable at reasonabletemperatures, preferably not significantly above50 C. The polyamide isalso preferably selected from among those having a refractive index ofabout L50, that is, as close as possible to the refractive index of thesurface layer to be applied, so that surface irregularities of thepolyamide will not be visible in the final product.

Among the polyamide resins that have given excellent results asintermediate layers between super strong bodies and surface layers ofabrasion resistant thermosetting resins are:

a. the solid thermoplastic fatty acid polyamides and the polyamidoaminesderived from the condensation of dimerized vegetable oil acids withdiamines or polyethylene polyamines;

b. aliphatic copolyamides based on combinations of polycaprolactam, poly(hexamethylene adipamide) and poly (hexamethylene sebacamide) in variousproportions;

e. nylons derived from the polymerization of capryllactam (Nylon 8); and

d. alkoxyalkyl substituted polyamides derived from poly (hexamethyleneadipamide).

These materials will be described in greater detail hereinafter.

DETAILED DESCRIPTION Representative embodiments of the invention willnow be described in greater detail in connection with the accompanyingdrawing, wherein the single FIGURE is a cross-sectional view of anophthalmic lens according to the invention during polymerization of itssurface layer.

A lens according to an illustrative embodiment of the invention as shownin the FIGURE includes a core 10 of bisphenol- A polycarbonate, arelatively thin surface layer 12 of diethylene glycol bis(allylcarbonate) polymerized in situ, and a bonding layer 14 of a polyamideresin between the core 10 and the surface layer 12. The bonding layer 14is applied in solution by dipping, brushing, or spraying. The solvent isevaporated and the body is then placed between mold halves 16 and 18,with a thin layer of diethylene glycol bis(allyl carbonate) monomeraround it. The monomer is then polymerized in situ. The mold halves l6and 18 are optically finished, and shaped in accordance with thecurvature desired for the finished lens so that only edging need be doneafter the lens is removed from the mold.

It has not been possible to apply coatings of abrasion resistantmaterials such as the allyl or methacrylic esters, or any otherrecognized hard and abrasion resistant resin directly on the phenolicpolycarbonate or on the ABS polymer, because the monomers of theabrasion resistant materials all attack the phenolic polycarbonate andthe ABS polymer chemically and opacify them. Also, the phenolicpolycarbonate and the ABS polymer are highly resistant to adhesives.Only very few materials are known that will stick to them.

The problem in polymerizing a hard coating resistant to abrasion on thetough cores was two-fold. The cores had to be protected against chemicalattack, and the coating material had to be securely bonded to them. Thesecond requirement was especially severe, because of the rigoroustreatment of the lenses during edging. Moreover, the barrier and bondingagent had to be transparent and colorless. I

It has now been found that many polyamides satisfy these requirements.The preferred polyamides are the solid thermoplastic fatty-acidpolyamides and polyamidoamines derived from the condensation ofdimerized vegetable acids with diamines or polyethylene polyamines. Forexample, thermal polymerization of unsaturated vegetable oil fatty acidsor esters from soybean, cotton seed, or corn oil, yields dimers,trimers, and higher polymers in complex mixtures commonly known as dimeracids. One typical dimer acid consists of 60 to 75 percent dimer acidssuch as the dimerized C acid derived from linoleic acid, and 5 to 20percent of trimers and higher polymers, plus a small amount of polybasicacid.

The mixture known as dimer" acids condensed with ethylene diamine givesa hard resin, whereas when it is condensed with an amine having afunctionality greater than two, such as for example, diethylenetriamine, it yields a softer, liquid resin which is of branched, ratherthan linear structure. The liquid resins are not by themselves useful inthe practice of the invention, but they may be used to advantage asadmixtures with the solid resins.

In addition to polyamides from polymerized vegetable oil acids condensedwith simple diamines and polyamines, many copolyamides are possible, andgive satisfactory results in the practice of the invention. Dibasicacids and polybasic acids can be added to the dimer" acid to modify theresulting polymer. Fatty acid polyamides in the molecular weight rangeof 3,000 to 10,000 are preferred, due to their solubility in alcohols atroom temperature. Higher molecular weight polyamides resulting fromcareful purification of the dimer acid to remove monobasic acids andpolybasic acids of functionality greater than two, yield, with adiamine, polyamides having limited solubility in alcohol at roomtemperature. Solutions of these resins in alcohols oralcohol-hydrocarbon mixtures may be applied to the polycarbonate coresin the practice of the invention at temperatures of about 50 C. andprovide satisfactory results.

Commercial resins that have been found to be particularly effective asbarrier and bonding agents on the polycarbonate and ABS cores are the900 series Versamid resins, the 1100 and 1112 Versalon resins, and theMilvex 1000 resin, all products of General Mills, Inc. These resins maybe used alone or in combination with each other. They differ from eachother primarily in molecular weight and in the composition and purity ofthe dimer acid used in their manufacture.

Another group of polyamides that have been found to i give good resultsin the practice of the invention are the aliphatic copolyamides based oncombinations of polycaprolactam, poly (hexamethylene adipamide), andpoly hexamethylene sebacamide) in various proportions. While thehomopolymers of these amides are not soluble in alcohol, the copolymersare soluble in mixtures of alcohol with chlorinated hydrocarbons at 50C. The solutions, however, tend to form gels at room temperature, and,therefore, are not as convenient to use as the preferred polyamides. t

A third group of polyamides, which is also suitable for use in thepractice of the invention, are nylons derived from the polymerization ofcapryllactam (Nylon 8) which have been found sufficiently solubleinalcohols for easy application to the polycarbonate and ABS cores.

A fourth group that has been found to give satisfactory results arealkoxyalkyl substituted polyamides derived from the alkoxylation of poly(hexamethylene adipamide) by reaction with formaldehyde followed byalkylation by reaction with a primary alcohol, resulting in a producthaving alkoxyalkyl side chains bonded to some of the backbone nitrogenatoms. One material of this type is the resin commercially designatedBCI Nylon 819 (Belding Chemical Industries). In general, the solubilityof these polyamides in alcohol depends in direct proportion on thedegree of substitution, the highly substituted materials being moresoluble. than the less substituted.

The thicknesses of the polyamide layer 14 and of the abrasion resistantlayer 12 are not critical in the practice of the invention. Typically,the polyamide barrier and bonding layer 14 is about 0.0001 inch to about0.001 inch thick, and the surface layer 12 is about 0.001 inch to about0.010 inch.

The polyamide layer is preferably made just thick enough to ensure thatit is impermeable to the monomer of the surface layer material; Anyadditionalthickness tends to impair its bonding ability, apparently dueto lack of adequate internal cohesion, or to changes in the distributionof strains within it. The preferred range of thickness for the layer ofpolyamide resin is, therefore, 0.0002 to 0.0004 inch.

The surface layer of the allyl polycarbonate must be thick enough tohave body," and to cover the entire lens despite differences in shapebetween the core coated with the polyamide resin and the cavity definedby the mold halves. Within this limit, it is preferably made as thin aspossible to minimize the tendency of the finished surface layer to crackand break off in response to a heavy impact on the opposite face of thelens. The preferred range of thickness for the surface layers in thepractice of the invention is 0.001 to 0.002 inch.

EXAMPLE 1 A core for a safety lens 3 millimeters thick and 55millimeters in diameter, and having both of its major surfaces lying oncurves of 6 diopters (zero refractive power) was injection molded in theconventional way of bisphenol-A polycarbonate. A solution was preparedconsisting essentially of 87.5 grams of polyamide resin commerciallydesignated Versalon l 100 dissolved in 330 ml. of isopropanol. Versalon1100 is a polyamide resin derived from dimer acid as hereinabovedescribed, and has a refractive index of 1.50 and a melting point of 105C.

The core was dipped in the solution at ordinary room temperature andwithdrawn at a rate of 1 inch per minute. It was then baked at 95 C. for1 hour to evaporate the isopropanol and leave a thin film of the resinon its surface.

The core with the thin film of resin on it was then coated with a thinskin of diethylene glycol bis(allyl carbonate) polymer by thepolymerization of the allyl monomer in situ upon both of its majorsurfaces. The allyl monomer was catalyzed with 12 percent isopropylpercarbonate based on the weight of the monomer. The procedure was asfollows.

A few millileters of the allyl monomer with the catalyst mixed into itwere placed into the female half of a horizontally supported opticallyground and polished mold. The resin coated core was then placed into thefemale half of the mold, forcing the monomer to run out into a thinlayer. A second quantity of the monomer was then placed in thedepression defined by the upper surface of the core, and the male moldhalf applied to it, forcing the added quantity of monomer to spread outover the upper surface of the core, between the core and the male halfof the mold. The mold was then placed in a spring clamp, which appliedabout 40 pounds total force and served to squeeze out air and part ofthe monomer. The assembly was then placed in an oven at 65 C. for 12hours to polymerize the allyl carbonate- Upon removal from the oven, thespring clamp was withdrawn from the mold, and the mold was treated in amethyl chloroform vapor degreaser for 20 seconds. The mold halves werethen forced apart by gently tapping the edges with a tool, leaving alens with surface layers of polymerized allyl carbonate, cemented inplace by the film of polyamide resin.

Optical imperfections in the outer surface of the layer of the polyamideresin were not visible in the final product because the refractiveindices of the polyamide resin and of the allyl carbonate polymer werevery closely matched.

The coated lens was then bevel edged by tungsten carbide tipped cuttersto conform to the shape of a standard safety lens, and tested for impactresistance. The test consisted of supporting it around its peripheryupon a strong support and firing a hardened steel ball /4. inch diameterat it at a velocity of 700 feet per second. The ball bounced off thelens without penetrating it or causing any fragments to be dislodgedfrom it.

EXAMPLE 2 This example is similar to Example 1, except that the initialinjection molded core was made of the clear ABS polymer as hereinabovedescribed, instead of bisphenol-A polycarbonate. The lens of ABS polymerwas treated in exactly the same way as described in Example 1 with thepolyamide resin and the allyl carbonate to provide a high impact safetylens with an abrasion and scratch resistant surface.

EXAMPLE 3 The starting core was of bisphenol-A polycarbonate and exactlysimilar to the core in Example 1. It was dipped into a solution of 100grams of Versamid 940 in 500 ml. of butanol maintained at 50 C. Versamid940 is the commercial designation of a polyamide resin made bycopolymerization of diand tri-linoleic acids with ethylene diamine. Thecore was withdrawn from the solution at a speed of one-half inch perminute, leaving a clear coating of the solution on it about 0.0002 -inchthick. The coated core was baked at 95 C. for 1 hour to evaporate thebutanol, and was then coated with a copolymer of 90 parts allyl diglycolcarbonate, and ten parts methylmethacrylate 54, polymerized in situ,applied as described in Example 1.

EXAMPLE 4 The core was of ABS polymer, as in Example 2. The polyamidesolution consisted of 300 ml. of n-propanol and 50 grams of type 8 nylonmade by polymerization of capryllactam, and was maintained at 50 C. Thecore coated with the polyamide was baked at C. for 2 hours to evaporatethe solvent, and was then coated with a polymer of ethyleneglycoldirnethacrylate with 0.5 percent by weight of isopropyl percarbonate asa catalyst, polymerized in situ. The monomer was applied as described inExample 1, and was cured by placing the assembly of the mold with itscontents and the clamping spring in an oven for 1 hour at 60 C. Uponremoval of the finished coated lens from the mold and cooling to roomtemperature, a highly satisfactory safety lens was produced, having highimpact resistance and fully commercially acceptable scratch and abrasionresistance.

EXAMPLE 5 The core was the same as in Example I, of bisphenol-Apolycarbonate. The solution consisted of ethyl alcohol containing 20percent by weight of an alcohol soluble nylon having approximatelyone-third of its -NH groups substituted with methoxy methyl groups (BClNylon 819). The solution was maintained at a temperature of 40 C., and acoating about 0.0002 inch thick was deposited on the outer surface ofthe core by dipping as hereinabove described. The coated core was thenbaked at 120 C. for 30 minutes to evaporate the alcohol. A surface layerof diethyleneglycol bis(allyl carbonate) was then polymerized in situ onit as described in Example I, using the allyl monomer catalyzed with 3percent benzoyl peroxide and curing for 16 hours at 90 C. The resultswere entirely satisfactory in all respects including impact resistance,optical properties, and abrasion resistance.

EXAMPLE 6 The core was of bisphenol-A polycarbonate as in Example 1. Thesolution consisted of warm methanol with 20 percent by weight of acopolyamide of nylon 6 6/6 6/ 10, available commercially as BCI Nylon651, by Belding Chemical lndustries. The copolyamide was applied anddried as described in the immediately foregoing examples. The final,abrasion resistant film consisted of a copolymer of 50 parts ofallyldiglycol carbonate and 50 parts triallylcyanurate polymerized insitu using a conventional catalyst and curing conditions. The resultingproduct was a commercially acceptable safety lens having the well knownabrasion resistance characteristic of the allyl plastic, the superimpact strength of the polycarbonate, and high quality opticalproperties.

EXAMPLE 7 (UNSATISFACTORY) The core was of bisphenol-A. polycarbonateexactly similar to the core in Example 1. An attempt was made to applyan abrasion resistant coating of allyldiglycol polycarbonate to it bypolymerizing the carbonate in situ without first applying a polyamideprotective layer. The monomer of allyldiglycol carbonate with 10 percentby weight of isopropyl percarbonate as a catalyst was pressed out into athin film upon the core by applying two glass mold halves having surfacecurves mating with the curves of the core as described in Example 1. Theallyl monomer was then cured by placing the mold assembly in an oven at60 C. for 12 hours. Upon removing the mold halves, it was found that thepolycarbonate core had been severely attacked by the allyl monomer andhad become almost opaque and, therefore, useless as a lens.

Not all of the polyamides that are soluble in alcohol oralcohol-hydrocarbon mixtures give satisfactory results in the practiceof the invention. The reason for this is not understood in terms of thechemical compositions of the polyamides. It appears, however, thatcertain of the commercially available polyamide compositions are noteffective, when applied as coatings in the preferred range of thickness,to protect the cores of the super strong plastics from attack by themonomers of the abrasion resistant surface materials. For example, thefatty dimer acid derived polyamides commercially designated Versalon1165 and Versalon 1140 have been found to be in this category and not toprotect the cores adequately when applied in layers thin enough toproduce the desired bonding strength between the cores and the surfacelayers.

It is a simple matter to ascertain the effectiveness of any particularpolyamide composition. It is first applied as by dipping and drying toform a coating of the desired thickness on a test piece of the corematerial. A small quantity of the catalyzed monomer of the desiredsurface material is then placed on the polyamide coating, and the testpiece is gently heated. If the polyamide composition is ineffective, thetest piece will show visible signs of chemical attack within a fewminutes, turbidity, and impairment of it optical clarity. If thepolyamide is effective, no visible impairment of the test piece willoccur.

What is claimed is:

1. A transparent body having a core of super strong plastic, an outersurface layer of an abrasion resistant thermosetting resin selected fromthe group consisting of allyl and methacrylic esters, and a bondinglayer of a polyamide between said core and said outer surface layer,said polyamide being one that is soluble in a solvent that does notattack said core, is substantially impermeable in a thickness of about0.0001 to 0.001 inch to the monomer of said thermosetting resin, and isselected from the group consisting of:

a. the solid thermoplastic fatty acid polyamides and thepolyarnidoamines derived from the condensation of dimerized vegetableoil acids with diamines or polyethylene polyamines;

b. aliphatic copolyarnides based on combinations of polycaprolactam,poly (hexamethylene adipamide) and poly (hexamethylene sebacamide) invarious proportions;

c. nylons derived from the polymerization of capryllactam (Nylon 8); and

d. alkoxyalkyl substituted polyamides derived from poly (hexamethyleneadipamide).

2. A transparent body according to claim 1 in which said core is ofbisphenol-A polycarbonate.

3. A transparent body according to claim 1 in which said core consistsessentially of a hetereogeneous blend of a. a gel fraction consistingessentially of a polymer of styrene-acrylonitrile-methylmethacrylategrafted onto a preformed rubber of styrene-butadiene,

b. a terpolymer of styrene-acrylonitrile-methylmethacrylate, and

c. a styrene-butadiene polymer, said gel fraction constituting about 30wgt. percent of said core.

4. A transparent body according to claim 1 in which said polyamide isselected from the group consisting of the solid thermoplastic fatty-acidpolyamides and polyarnidoamines derived from the condensation ofdimerized vegetable acids with diamines or polyethylene polyamines, andmixtures and copolymers thereof.

5. A transparent body according to claim 1 in which said polyamide is analiphatic copolyamide based on a combination of polycaprolactam, poly(hexamethylene adipamide), and poly (hexamethylene sebacamide).

6. A transparent body according to claim 1 in which said polyamide is anylon derived from the polymerization of capryllactam.

7. A transparent body according to claim 1 in which said polyamide is analkoxyalkyl substituted polyamide derived from poly (hexamethyleneadipamide).

8. A transparent body according to claim 1 in which said surface layeris an allyl carbonate.

9. A transparent body having a core of super strong plastic, an outersurface layer about 0.001 inch to about 0.010 inch thick of an abrasionresistant thermosetting resin selected from the group consisting ofallyl and methacrylic esters, and a bonding layer of a polyamide about0.0001 inch to about 0.001 inch thick between said core and said outersurface layer, said polyamide being one that is soluble in a solventthat does not attack said core, is substantially impermeable in athickness of about 0.0001 inch to 0.001 inch to the monomer of saidthermosetting resin, and is selected from the group consisting of:

a. the solid thermoplastic fatty acid polyamides and thepolyarnidoamines derived from the condensation of dimerized vegetableoil acids with diamines or polyethylene polyamines;

b. aliphatic copolyamides based on combinations of thickness of about0.0002 inch to 0.0004 inch to the monomer polycaprolactam, poly(hexamethylene adipamide) and of said thermosetting resin, and isselected from the group poly (hexamethylene sebacamide) in variousproportions; consisting of: c. nylons derived from the polymerization ofcapryllactam a. the solid thermoplastic fatty acid polyamides and the(Nylon 8); and polyamidoamines derived from the condensation of d.alkoxyalkyl substituted polyamides derived from poly d merized vegetableoil acids with diamines or (hexamethylene adipamide). polyethylenepolyamines; 10. A transparent body having a core of super strongplastic, aliphatic copolyamides bascd on combinations of an outersurface layer about 0.001 inch to about 0.002 inch Polycaprolactam, P y(hexamflhyknc adipamide) and thick of an abrasion resistantthennosetting resin selected 10 P y (hexamethylene Sbacamid)il1 VariousP P from the group consisting of ally] and methacrylic esters, and anylons delived from the Polynm'ization of capfyllactam bonding layerof apolyamide about 0.0002 inch to about y )z 0.0004 inch thick between saidcore and said outer surface alkoxyalkyl subsumted polyamdes demmd from Player, said polyamide being one that is soluble in a solvent that(hcxamethylcne adlpamlde)- does not attack said core, is substantiallyimpermeable in a

2. A transparent body according to claim 1 in which said core is ofbisphenol-A polycarbonate.
 3. A transparent body according to claim 1 inwhich said core consists essentially of a hetereogeneous blend Of a. agel fraction consisting essentially of a polymer ofstyrene-acrylonitrile-methylmethacrylate grafted onto a preformed rubberof styrene-butadiene, b. a terpolymer ofstyrene-acrylonitrile-methylmethacrylate, and c. a styrene-butadienepolymer, said gel fraction constituting about 30 wgt. percent of saidcore.
 4. A transparent body according to claim 1 in which said polyamideis selected from the group consisting of the solid thermoplasticfatty-acid polyamides and polyamidoamines derived from the condensationof dimerized vegetable acids with diamines or polyethylene polyamines,and mixtures and copolymers thereof.
 5. A transparent body according toclaim 1 in which said polyamide is an aliphatic copolyamide based on acombination of polycaprolactam, poly (hexamethylene adipamide), and poly(hexamethylene sebacamide).
 6. A transparent body according to claim 1in which said polyamide is a nylon derived from the polymerization ofcapryllactam.
 7. A transparent body according to claim 1 in which saidpolyamide is an alkoxyalkyl substituted polyamide derived from poly(hexamethylene adipamide).
 8. A transparent body according to claim 1 inwhich said surface layer is an allyl carbonate.
 9. A transparent bodyhaving a core of super strong plastic, an outer surface layer about0.001 inch to about 0.010 inch thick of an abrasion resistantthermosetting resin selected from the group consisting of allyl andmethacrylic esters, and a bonding layer of a polyamide about 0.0001 inchto about 0.001 inch thick between said core and said outer surfacelayer, said polyamide being one that is soluble in a solvent that doesnot attack said core, is substantially impermeable in a thickness ofabout 0.0001 inch to 0.001 inch to the monomer of said thermosettingresin, and is selected from the group consisting of: a. the solidthermoplastic fatty acid polyamides and the polyamidoamines derived fromthe condensation of dimerized vegetable oil acids with diamines orpolyethylene polyamines; b. aliphatic copolyamides based on combinationsof polycaprolactam, poly (hexamethylene adipamide) and poly(hexamethylene sebacamide) in various proportions; c. nylons derivedfrom the polymerization of capryllactam (Nylon 8); and d. alkoxyalkylsubstituted polyamides derived from poly (hexamethylene adipamide). 10.A transparent body having a core of super strong plastic, an outersurface layer about 0.001 inch to about 0.002 inch thick of an abrasionresistant thermosetting resin selected from the group consisting ofallyl and methacrylic esters, and a bonding layer of a polyamide about0.0002 inch to about 0.0004 inch thick between said core and said outersurface layer, said polyamide being one that is soluble in a solventthat does not attack said core, is substantially impermeable in athickness of about 0.0002 inch to 0.0004 inch to the monomer of saidthermosetting resin, and is selected from the group consisting of: a.the solid thermoplastic fatty acid polyamides and the polyamidoaminesderived from the condensation of dimerized vegetable oil acids withdiamines or polyethylene polyamines; b. aliphatic copolyamides based oncombinations of polycaprolactam, poly (hexamethylene adipamide) and poly(hexamethylene sebacamide) in various proportions; c. nylons derivedfrom the polymerization of capryllactam (Nylon 8); and d. alkoxyalkylsubstituted polyamides derived from poly (hexamethylene adipamide).